Android- Open new activity on listview clicks

Im trying to make it so that when i click specific items in my listview, it will take me to specific screens. Does anyone know how to do this? Im using the code below for this

Furthermore. Im trying to make a single back button appear at the bottom of the listview. So far i can only make it appear on every entry in the listview, help would be greatly appreciated!

import android.app.Activity;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class Advertise extends ListActivity {

    /** Called when the activity is first created. */
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        // Create an array of Strings, that will be put to our ListActivity
        String[] names = new String[] { "Linux", "Windows7", "Eclipse", "Suse",
                "Ubuntu", "Solaris", "Android", "iPhone" };
        // Use your own layout and point the adapter to the UI elements which contains the label
        this.setListAdapter(new ArrayAdapter<String>(this, R.layout.advertise,
                R.id.label, names))开发者_C百科;


    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        // Get the item that was clicked
        Object o = this.getListAdapter().getItem(position);
        String keyword = o.toString();
        Toast.makeText(this, "You selected: " + keyword, Toast.LENGTH_LONG)
                .show();


        {

        } 
    }
}

Start Activity this way.

Intent intent = new Intent("com.mysite.myapp.SOME_NEW_ACTIVITY");   
startActivity(intent); 

You don't need back button in the ListView, your hardware 'Back' button will do the same.